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Displacement from bitmap

(280 total words in this text)(6562 Reads)

tips and tricks

Displacement from bitmap

by
Chris Mungenast and Mark Heuymans

Chris Mungenast:

Make a material with a surface geometry shader. Add a bump object and setthe bump height. Take the sds object, go to the spec tab/rendering and make the max displacement the same value as the material bump height. Also make sure there is enuff vertex density to allow some deflection. It does not do
micropoly displacement. If you don't see anything, try ramping up both
height values til you do.

Mark Heuymans:

"Look at the VSL. There's a Surface Geometry shader because we need a Bump height channel. Only 3 lines of code in that shader:

Bump Height = Texture(Map Coords)
First assign the texture to Bump Height. Set Gradient to force it to use
float values (I always do that using bump height textures). The values
obtained are between 0.0 and 1.0 (not 255!). That's not good. Firstly ,
it's best to use zero displacement in the middle of the possible bump
height values. So, we substract 0.5 from the current bump height:

Bump Height -= Constant(0.5)
Note : '-=' : substract!. Another way to do this would be a Linear object:
Bump Height = Linear (Bump Height), multiply = 1.0 and Add = -0.5. Or an
operation: substract variable 0.5 from bump height. Anyway: now we have
bump height values ranging from -0.5 to +0.5. Neutral grey = zero
displacement. This is still not good, it's too much. So:

Bump Height = Linear (Bump Height)
This determines the final displacement range, the object's Max displacement
should be near this. I chose a multiplication of 0.05.